1. Technical Field
The present invention relates to a droplet discharge device and a droplet discharge method for discharging liquid in the form of droplets.
2. Related Art
Conventionally, ink jet printers are known as one kind of droplet discharge device. Ink jet printers perform printing by causing ink (liquid) to be ejected in the form of ink droplets (droplets) from a liquid ejection head (an ejecting section) toward a sheet (a medium) and to be adhered onto the sheet (see, for example, JP-A-2007-30363). It is also known that, in such printers, a shift in ink droplet adhesion position on a sheet occurs, for example, in a case where a liquid ejection head is mounted in the printer in an inclined state from a proper posture.
Such a shift in ink droplet adhesion position may undesirably cause a decrease in printing accuracy such as color irregularities in a printed image on a sheet. Conventionally, such a shift in ink droplet adhesion position is checked as follows. Specifically, a linear test pattern is formed on a sheet by causing a plurality of nozzles (discharge openings) that constitute a nozzle array of a liquid ejection head to discharge ink droplets onto the sheet while moving the liquid ejection head and the sheet relative to each other, and the actual degree of such a shift in ink droplet adhesion position is checked on the basis of the test pattern thus formed. In a case where it is determined that a shift in ink droplet adhesion position has occurred, the shift in ink droplet adhesion position is corrected through an adjusting operation such as correction of inclination of the liquid ejection head.
A shift in ink droplet adhesion position is judged by comparing (i) an ideal supposed pattern that is supposed to be formed on a sheet in a case where a liquid ejection head is correctly mounted at a proper position without inclination and (ii) a test pattern that is actually formed on a sheet by discharge of ink droplets. However, this method has a problem that in a case where the degree of the shift in ink droplet adhesion position is very small, it is difficult to judge such a very small shift.
This problem is common to not only ink jet printers but also droplet discharge devices in general which discharge liquid in the form of droplets.